Inasmuch as different countries use different systems of weight units, there is a need in the manufacture of weighing scales to provide a scale in which alternative systems of weight units can be displayed such as, for example, ounces and pounds under the English weight unit system, or grams and kilograms under the metric system.
In a conventional beam scale such as is used for weighing people or other objects, including clinical scales, chair scales, scales used in physicians offices, personal beam scales, as well as beam scales used in weighing objects, the conventional types of scale have index bars on which poise weights are slidably mounted with the weight units displayed on the front of the bar, the beam being balanced on a fulcrum pivot and having a power pivot responsive to weight on a weighing platform. The slider is moved on the index bar until the beam is in balance. Usually, for weights up to 350 pounds there are two index bars, one above the other, the top bar carrying a small poise weight slider and the lower bar carrying a large poise weight slider. The weight readings on the upper bar may go as high as 50 pounds while the weight readings on the lower bar may go from 50 pounds to 350 pounds. It is not very practical to display different types of weight units such as weight units in the English system and weight units in the metric system so that the user can move the poise weights to the proper position for determining weight in two different types of weight units.
One system has been suggested whereby English weight units are exhibited on the front of the index bars and metric are exhibited on the back of the index bars but this is not very practical because in many cases weighing scales are placed against walls or in out-of-they way places where they cannot be viewed and operated from the rear. Furthermore, a user standing on the scale from the front where the scale exhibits weight in English units on the front of the index bars and in metric units on the back of the bars would have to move the poise weights until the beam balances and then determine the weight in metric units by stepping off of the weighing platform and going to the rear of the scale. This system also requires that the notches which normally are placed on the top of the index bar at predetermined positions corresponding to rather large weights in the case of say 50 pounds, 100 pounds, 150 pounds, etc., also be provided in different denominations and different locations for the metric system.